Effect of peracetic acid and aldehyde disinfectants on biofilm.

The effects of two aldehyde (Cidex, Endosporine) and four peracetic acid (PAA) (Nu Cidex, Anioxyde 1000, Hydraseptic, Peralkan) disinfectants on an Escherichia coli biofilm model were studied. The biofilm was prepared in glass tubes, and evaluated indirectly using a colourimetric method. The ability of the disinfectants to fix or remove the biofilm from tubes was determined by their detergent activity (DA). The two aldehyde derivatives and two of the PAA (Nu Cidex, Anioxyde 1000) agents fixed the biofilm. However, the effects of Hydraseptic and Peralkan were equivalent to the control (sterile water). Regardless of their disinfectant activity, PAA agents display different DAs that could be used to select the weakest biofilm-fixing agents. Users should be concerned about the efficiency of the cleaning stage of medical devices, and when choosing a PAA product, non-fixing ability should be considered in addition to antimicrobial activity.

Effectiveness of detergent-disinfecting agents on Escherichia coli 54127 biofilm.

Detergent-disinfecting agents (dD) are used daily for cleaning reused medical devices. We have devised a simple method to test dD detergent activity (DA) using an E. coli 54127 biofilm prepared in haemolysis glass tubes, which are cleaned with test dD, according to supplier's recommendations. Crystal violet 0.05% is used to colour the residual biofilm after dD (or tap water control) application. The biofilm quantification was made indirectly by measuring the absorbance of crystal violet at 585 nm. A measure of the detergent effectiveness called DA was calculated as the percentage reduction of colour from a tap water control. Fifteen products including enzymatic and non-enzymatic dDs were evaluated. Most enzymatic dDs gave a high DA, as did some non-enzymatic products. Thus, the view that enzymatic dDs are more effective than non-enzymatic dDs, put forward by some manufacturers, should be regarded with caution. The DA determination should help infection control teams choose, within the wide range of products available on the market, the most effective dD based on both its detergent and disinfecting activity.

[What are the indications in France for vaccination against Japanese encephalitis?]. / Comment poser en France l'indication de la vaccination contre l'encéphalite japonaise?

Japanese encephalitis is a mosquito-borne viral disease occurring in rural and rice-growing areas of Asia, where mosquitoes proliferate, transmitting the Flavivirus from viremic animals, mostly pigs, to humans. Japanese encephalitis has recently spread to previously non-affected regions, leading to serious outbreaks among non-immune populations. Although it has a high proportion of unsymptomatic infection, clinical encephalitis is usually severe, resulting in a very high mortality rate, and neurologic sequellae are common among survivors. Vaccines are used in several Asian countries. One of these vaccines is now available to French travellers, but only in international vaccination centres with an authorization from the French drug agency (Agence française de sécurité sanitaire des produits de santé). The aim of this paper is to clarify the recommendations for immunisation in each country of the affected regions. The area can be divided into three epidemiological zones, with tropical, subtropical and temperate characteristics. For the first two, vaccination is recommended before a long stay in a rural area, especially during the rainy season; in temperate climates, outbreaks occur in summer and autumn. However, local variations such as intensive rice-growing or development of pig breeding may interfere with these patterns. Long-term visitors should consult a local physician and prevention of mosquito bites is always recommended.

[Role of hygiene and bacteriological laboratories in the management of an epidemic of Enterobacter aerogenes multiresistant to antibiotics]. / Rôles des laboratoires d'hygiène et de bactériologie dans la prise en charge d'une épidémie à Enterobacter aerogenes multirésistant aux antibiotiques.

We describe a multiresistant Enterobacter aerogenes outbreak in an intensive care-unit. An epidemiology study based on phenotypic characters (species diagnosis and antibiotype) was completed by a genotypic study (pulsed field electrophoresis) to confirm bacterial clonality. The hygiene laboratory proposed numerous preventive measures to limit bacterial dispersion. We describe the role of bacteriologists, hygienists and medical staff to stop the bacterial dispersion.

[Quantitative bacteriological evaluation of a method for skin disinfection in blood donors]. / Evaluation bactériologique quantitative d'une méthode de désinfection cutanée chez les donneurs de sang.

Skin disinfection at the site of venipuncture is a critical point in every blood transfusion collection procedure, as it contributes to ensure the bacterial safety of transfusion. Quantitative and qualitative analysis of bacteria present in the antecubital fossae before and after skin disinfection may be one method of assessing the anti-bacterial efficiency of disinfection. Swab culture systems and contact plates are the two techniques usually employed for this purpose. A washing and swabbing technique was used to quantify bacteria before and skin disinfection of the antecubital fossae in blood donors. This contra-placebo study was carried out on 32 donors, each of whom served as his own control, with a random choice of test arm and opposing control arm. Bacterial counts were determined in the antecubital fossae without skin disinfection (control, n = 32) and after a 3 step skin preparation procedure (cleaning, wiping, disinfection) using placebo (distilled water, n = 16) or an antiseptic product (mixture of chlorexidine, benzalkonium chloride and benzylic alcohol, n = 16). The absence of a statistical difference in bacterial counts between the right and left antecubital fossae without disinfection was controlled in a preliminary study of 20 subjects. Mean bacterial counts were 25,000/cm2 and 27,400/cm2 respectively for aerobic and anaerobic bacteria before disinfection, with a wide variation in results between individuals. When using placebo, preparation of the venipuncture site by the 3 step method (cleaning, wiping, disinfection) resulted in a non significant mean reduction of 0.56 log in aerobic and anaerobic bacteria. Using the antiseptic product, the same method resulted in a significant mean reduction of 1.8 and 1.7 log respectively in aerobic (p = 0.015) and anaerobic flora (p = 0.005). On an average, 2,750 aerobic bacteria/cm2 and 2,910 anaerobic bacteria/cm2 remained after disinfection, while qualitative analysis showed that disinfection suppressed the transitory flora in all cases but left part of the resident flora in 12/16 cases. These findings are comparable to those of other studies carried out to evaluate this kind of technique for the disinfection of operation sites. In comparison with other techniques classically employed for this type of evaluation (swab systems or contact plates), the method used in this study was the advantage of allowing the quantification of the reduction in bacteria. Hence this method could be employed for comparative assessment of skin disinfection techniques with the aim of improving their anti-bacterial efficiency and could also make possible the definition of a minimum bacterial count (resident flora) to be obtained in all cases after disinfection.

[General rules of infection prevention in organ transplantation, bone marrow transplantation and prosthetic surgery]. / Les règles générales de la prévention de l'infection dans les greffes d'organes, de moelle, et la chirurgie prothétique.

General rules to prevent are categorized into four classes. The first one concern patient before operation: well-balanced nourishment latent infections treatment, digestive tract micro flora elimination, immunizations, antiseptic gargles, skin antisepsis. The second one concern operation: previous fumigation, very high efficiency filtration and laminar flow air, transplant care, antibioprophylaxis, operating theatre discipline. The third one concern post-operation days: cubicle initial fumigation, high efficiency filtration and positive pressure air, strict protective insulation, single-use things, controlled food, specific anti viral prevention, catheters and tubes removal or replacement. The fourth one concern going home patient: well-balanced nourishment, body hygiene and hands washing, infected people shunning, gardening and cleaning proscribing, medical follow-up and latent infections systematic detection.

[Bacteriological control of food for immunocompromised host]. / Contrôle bactériologique des aliments pour immuno-déprimés.

This study concerning bacteriological controls of food for immuno-suppressive patients have shown that food sterilized in sterilizer or with pressure-cooker contains sporulated bacteria after treatment. Unit packaging or freeze-drying commercial foods offer no bacteriological quality guarantees. Clinicians have to define acceptable contamination rate according to their patients' condition.

[Does automatized disinfection of traps by chlorine reduce water related contamination?]. / La désinfection automatisée des siphons par le chlore réduit-elle la contamination d'origine hydrique?

Sanitary U bends are very contaminated places from a microbiological point of view. They may even be dangerous for immunocompromised patients. Although daily chloride disinfection of U-bends is ineffective, it seems to work when performed after each use of sanitary devices. On line disinfection reduces not only U-bend bacteriological contamination but also all surrounding surfaces.

Pulsed field gel electrophoresis as a new epidemiological tool for monitoring methicillin-resistant Staphylococcus aureus in an intensive care unit.

Pulsed field gel electrophoresis (PFGE) of bacterial DNA was used in a 1-month epidemiological study of methicillin-resistant Staphylococcus aureus (MRSA) in a 15-bed Intensive Care Unit (ICU). Patient and hospital staff carriage as well as distribution of MRSA in the ICU environment were investigated, and a total of 3802 samples produced 175 isolates. The stability and the reproducibility of the PFGE method were satisfactory. Moreover, the plasmid content of the strains so far examined had no influence on the PFGE profiles of the MRSA strains. The polymorphic profiles observed also account for the use of this method as an epidemiological tool for investigating MRSA. Among 30 patients who stayed more than 4 days in the unit, PFGE analysis showed 11 episodes of colonization in nine patients, whereas lysotyping and plasmid DNA analysis demonstrated only eight and seven such episodes in the same patients, respectively. The combination of PFGE with lysotyping and plasmid analysis may provide a greater discriminatory capacity between MRSA isolates.

[Cost of infection in intensive care units]. / Le coût de l'infection en réanimation.

Different methods are used to value nosocomial infections: direct valuation, simple comparison, case control study, standardized comparisons with adjustments. The cost of preventive methods need to be considered and integrated in cost-effectiveness analysis.

[Evaluation of the cost-efficacy ratio of Pall BB 22 15 filters for the bacterial protection of anesthesia circuits]. / Evaluation du rapport coût-efficacité des filtres Pall BB 22 15 dans la protection bactérienne des circuits d'anesthésie.

The aim of this study is to assess wether the use of the bacteriological filter Pall BB 22 15 placed on the Y piece of the anesthesia equipment decreases contamination and furthermore to evaluate the cost of this practice versus changing anesthetic circuits after every patient. Randomized trials are conducted with three "Engström" machines in three cardiac surgery operating rooms. The Y pieces were examined with qualitative and quantitative bacteriological analysis. Use filters is less expensive than changing circuit for each patient for a comparable efficacy.

[Contamination of bronchial fiberscopes by mycobacteria. Myth or reality?]. / Contamination des fibroscopes bronchiques par les mycobactéries. Mythe ou réalité?

The authors report the results of a study into mycobacterial contamination of bronchial fibroscopes over a 6 year period during which 8,750 fibroscopies were performed. On 19 occasions, there were two positive results on the same day which could have led to contamination (0.07 p. 100). In 12 cases, there was heavy bacterial contamination on the first examination and at least 5 colonies on the second. Crossed transmission was not observed. The authors emphasize the role of the accessory parts and connections which are often neglected and which may lead to false positive results in the following patients; a sterilisation procedure is proposed which seems to be effective as no mycobacterial contamination has been observed since it was introduced.